Which species of water frogs inhabit ponds of the Caucasus? Taxonomic mess with Pelophylax ridibundus species complex

Abstract

Two nominal species of water frogs of the genus Pelophylax, P. ridibundus and P. bedriagae, are found in Central and Eastern Europe, the Middle East, Western Asia, Western Kazakhstan, and Siberia. So far, the taxonomic status of Pelophylax in most of the Caucasus has remained unknown. Sequencing of the Cytochrome Oxidase 1 mitochondrial gene attributed the frogs throughout Georgia to the P. ‘bedriagae’ lineage, bringing them very close to the specimens from Kazakhstan and Greece. Simultaneously, the current nomenclature of water frogs appears to be formally incorrect since western Kazakhstan, the type locality for P. ridibundus, has frogs genetically closer to nominal P. bedriagae, than to nominal P. ridibundus from Europe. Because there is no evidence that the frogs from Central Europe, Kazakhstan, and the Caucasus, as well as from Anatolia and Iran, are biological species with individual evolutionary pathways, we suggest a conservative approach and synonymize nominal P. bedriagae from most of West Asia with P. ridibundus.